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  <title>Document</title>
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<body>
  <script>
    let a
    let b,c,d
    let e = 500
    let f = 123, g = "iloveyou"
    //1、变量不能重复声明
    let star = "zbj"
    // let star = "swk"

    //2、块级作用域
    //if eles while for
    // {
    //   let girl = "bgj"
    // }
    // console.log(girl)

    //3、不存在变量提升
    // console.log(song)
    // let song = "zzj"

    //4、不影响作用域链
    {
      let school = "shangguigu"
      function fn(){
        console.log(school)
      }
      fn()
    }
  </script>
</body>
</html>